You answered: Medullary thyroid carcinoma
That is CORRECT!!
This is a highly cellular specimen containing a mainly dispersed population of pleomorphic cells. The nuclei are round to oval and occasionally spindle-shaped, with granular salt and pepper chromatin best seen in the Papanicolaou stained material.
- In the MGG stained material red neuroendocrine cytoplasmic granules are identified, as well as occasional intranuclear inclusions. Dark blue amorphous material is most likely amyloid.
- These cytologic features are consistent with a medullary carcinoma of the thyroid.
- The biopsy reveals solid sheets and nests of large, polygonal malignant cells with amyloid deposits within a highly vascularised stroma
- Medullary carcinoma is a neuroendocrine type malignant tumour comprising approximately 5-10% of thyroid carcinomas. Thought to arise from parafollicular C cells, tumour cells produce calcitonin which may be demonstrated by immunocytochemistry. Elevated serum levels of calcitonin in conjunction with a thyroid nodule are virtually pathognomonic of medullary carcinoma. Approximately 20% of cases are familial. They tend to present at a younger age, may be bilateral and may occur as part of multiple endocrine neoplasia (MEN) syndrome. However, the majority of cases are sporadic with a mean age range of 30-50 years and a slight female predominance.
- On tissue sections, tumour cells are usually polygonal but may be spindled or small and round in a carcinoid-like pattern. Giant cells, clear cell, melanotic, mucinous and oncocytic forms have also been identified.
- Amyloid is a characteristic component of medullary carcinoma but the amount of amyloid within the tumour is variable. On cytology, material stains purplish blue on Giemsa stains and pale green-blue on Papanicolaou stain. Tumour cells are often very closely associated with amyloid, a feature that may help distinguish it from colloid.
- Intranuclear inclusions seen in up to 50% of medullary carcinomas may be a pitfall, suggesting papillary carcinoma. Identifying red neuroendocrine cytoplasmic granules on air-dried Giemsa stained material and the coarser granular chromatin will help with this differential diagnosis.
- The aspirate usually lacks the microfollicular pattern typical of a follicular neoplasm, which also tends to demonstrate more uniform, round nuclei than that of medullary carcinoma. The characteristic salt and pepper chromatin pattern also supports the diagnosis of a neuroendocrine carcinoma.
- Markedly pleomorphic, bizarre tumour cells often present in anaplastic carcinomas are rarely seen.
- The cytologic diagnosis of medullary carcinoma is best supported by immunocytochemical stains for calcitonin and other neuroendocrine markers, as well as serum analysis for calcitonin.
BACK TO IMAGES
Geisinger KR, Stanley MW, Raab SS, Silverman JF, Abati A. Modern Cytopathology. Elsevier Churchill Livingstone; 2004, pp759-764.
McKee GT. Cytopathology. Mosby-Wolfe Times Mirror International Publishers Limited; 1997, pp104-107.
Demay, Richard M. The Art & Science of Cytopathology: Chicago: ASCP Press, 1996. pp735-737